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Tribune Extras Lecture and Letter Scries. 



tion. Therefore it may ?>:om quite different. But we may 

 a<luiit, however, and it would bo most important 

 Indeed for chemists to make re-i-.irehcs in tliut respect 

 we may admit that a chemical t-hango is the iv.-ult of 

 tbat transformation ; that t!ie nerve foive is ['-.insioi-nied 

 Into a chemical force, and that cln-Miir.il changes oeeur 

 lu the coll, very rapnllv a. id in great quantity, pi>t 

 CiioiiL'h to replace tin- whole amount ol iierv.- i.nv iliat 

 was acting lr I'.ne. Then-ton-, t le-re i> no reason a priori 

 not to aduilt tho possibility and tin* probability that 

 nerve force i < rho .same in every m>t nice ; that it nff-cts 



cells of gray matter to stop them in the same w.u that 



it can put cells into activity ; in the .-ame way that it 



can put muscles into aotirltyi and that it cau put an 

 organ uto activity. 



NERVOUS INFLUENCE SECOND LECTUEE. 



SOME OF Till: 1'AtT.S THAT AKF. I'll 1 ICULT TO KX- 



ri.Aix A M:I;KO 1:1 \>\ i i:s CONVULSIONS KY 

 PI/LI.IM; AT mi: cui AT TDK MOKE PEKSISTKNT 



VITAI.I1V IN AMERICA MIAN IN KUUOl'E, I1OTH 

 1\ MI.N \M> A Si M ALS VARIOUS RELATIONS BE- 



TWKKN TIM; M:i:v(rs srsTKM AND THE ACTION 



OF THE Ill.AKl MI.IIIODS OF CHECKING CON- 

 VULSIVJ. EFFORTS, -I II AS COUGHING. AC. 



BOSTON, M.ncli 1. Dr. Biowri-.Se'quard delivered 

 hia second lecture to a large audience : 



LADIES AM> LI M I.I.VI.N : In tho lasc lecture I tried 

 to t-how 8c-ver.il points relating to the force which we 

 kuow to exist in nerv es. I particularly insisted on what 

 I call the unity ol lorco in the nervous system. I espe- 

 cially tried to show that every nervous action is tho 

 caii-eof.in expenditure of nervous force. There are a 

 lew 1'aets, however, whieh may be considered aa const i- 

 tut i n g an olije, -non to t'laf. I will mention some of them. 

 Tiie principal one is, that we kuow full well that certain 

 parts of the bmiv may be extremely weak while otlr-rs 

 remain strom.'. JJut that certainly is no objection, Mn.-e 

 if we admit that the communication Is obstructed be- 

 tween the, part whieh is weakened and the rest, it is 

 quite natural tint there should bo a diminution of force 

 lu that part. Besides this, then) is something in the 

 iiei vons p\ Mem ;i.s we.ll as in the muscles that permits a 

 reaction after an irritation. There is a proporty'of nerv- 

 ous tl.--ne ami muscles especially which wo call excita- 

 bility. Tho exejtability of the nervous system is entirely 

 and ah.solule.v imlepeii.leiif of the amount, of nervous 

 force. ivrhaps, it i.s wrong, however, to say as 

 I have just done, that there is 110 dependence 

 of one upon tlie other. Thf-re may be a dependence iu 

 this way, that the greater tho amount of nervous foive, 

 the lets excitability there is, and rice rcrsa, the greater 

 the amount oi e \eii .ilninv thu less amount of nervous 

 force, i'eopir \\lio IMVI- be-ii ill; people who arc nat- 

 urallv cxtiemely weak, or UIOM- who have lost a good 

 deal of blood and hare been v. e.;Kene<l iu that way; iu 

 other words, people who have \ery littlo uervo force, 



are, as is well known, exlremi'l\- i-x.'itablc. They will 

 Jump at a inii-e an I in other ways .show nervousness. 

 There is, then-tore, MHIICI Inni: ijuilo distinct iu these 

 two things exi ilabiil: y and nerve force. Tins property 

 of e\citalln i- nothing lull the power to receive an e\ - 

 citation. 1'cr- ins w ho are i-xliemelv stroni,', will not 

 Kent-rally be moved by exeiialion. Thev will, of course, 

 l\UUreei,ite the <-X' llatlon; they will Jndx'e what H i ; 

 but tliuv will remain calm under it.. \Vhlle, on ilr- OOD- 

 trury. persons who.-e nt-i vous .system Id weak, and who 



have little nerve force, will react under any excitation, 

 however slight, without Kivin~ to the mind time to 

 think of what i he excitation is. 



Isaldinuiy last lecture that the nervous force is 

 quite dill, M ut from electricity, that it is a lorce by itself; 

 but I must add to this .statement another ouu. that ttio 

 nervoii> >y-i, in i.s more or less charged \\i;n electricity 

 all the time in health. The tww forces, electricity aul 

 m-rve power, are both present; but not alwava iu proijor- 

 tion olio to the other, as sometimes then' may be an 

 op;iosiic condition. JSut certa'uly the nerve force ia not 

 electricity, as we well know that the spei-.l of the nerve 

 i "ice is only from 80 to 300 feet iu a si-con 1, while tho 

 speed of electricity as you kuow is thousands and thou- 

 sands of times greater. 



Till: INTI.ULXCE THAT IS EXERTED UPON THE NEUVE3. 



I now come to tho principal objocc of this lecture, 

 which introduces a suhj -ct that must extend to one or 

 two more lectures that is, tho mllaeueo that tho 

 nervous system exerts upon it.-elf by the force that wo 

 call nerve lorce. There are two Kinds of such influence, 

 which are absolutely distinct one from the other. One 

 consists in the pro'hu-ti.ni of the activity, either normal 

 or morbid; tho other consists in the cessation of tho 

 morbid or normal activity. These t\v. nn-at influences 

 of nerve force, acting upon parts at a distance more or 

 less irreat, cover almost all the facts relating to the in- 

 fluence of the nervous system upon itsc-lf. I shall this 

 evening enter more fully into tho history of facts which 

 show that tho nervous system can stop the actiou of a 

 part of its extent. All wo know on this subject is of 

 comparatively recent discovery, and tho principal fact 

 developed is that which relates to tho iisart. Tho 

 brothers Webber discovered that tho heart in a per- 

 lectly healthy man may bo stopped suJdcnly iu ita 

 actiou in a way which is quite difi'ercut from 

 that which reirards muscles generally. If we 

 galvanize a muscle that has been more or less 

 in contraction by a current passing to and fro, stopping 

 and passing again, so that the muscle is contracting and 

 relaxing, as I show you now in this movement up and 

 down exerted by tho front of my ar:n .suppose that this 

 is acting, and I pass a current into the nerves that goes to 

 the uiusfles thus acting immediately tho IUOVCUIL-UG 

 stops; so that there is something similar to tho 

 cessation of the action of tho heart. But tho action 

 stops, not because the muscles have stopped acting. Ou 

 tho contrary, tho muscles are acting with a wonderful 

 power, tho greatest that they may have under tho 

 amount of electricity that is pasMuir; and the contracriou 

 remains perfectly fixed so long as the current passes. 

 This is the production of an active state in tho muselo, 

 and not the production of a passive state. According to 

 the discovery of tho brothers \\vnl >er, when the big nerve 

 in the neck that goes to the heart, and which we call tho 

 pur tngnm, is thus influenced, the heart slops, passively, 

 not act ively, like the muscles of my arm. Tho walls of 

 the heart remain perfectly llaeeid, perfectly motionless 

 from want of activity. During that time tho heart is 

 Illh-d more and more by blood reaching it, and it becomes 

 very much distended after a short tim -, as it .dues not 

 reject the blood it is constantly receiving. Tiioro is, 

 therefore, in that stoppage of tho heart's uc- 

 tion a phenomenon qr.ito peeiili.ir. And it is 

 a phenomenon which implies a c ita.n kind of 

 act i vity. For although then- i> a passive- elleet obtained, 

 u passivity produced in the heart, there is ati activity lu 

 the nerves that tro to the heart to produce ih.it cessation. 

 T. it-re Is an intluence upon c. rtain parts ul tin- lu-.irt be- 

 longing t;> I lie nervous system, and it is ccrt.::u!y au ac- 



